The make_figure (S-Lang or Python help) and add_curve (S-Lang or Python help) commands can plot data from a file (in both FITS binary and ASCII formats).

1. Two columns: A set of (x,y) points.

   # Python
     make_figure("file.lis[cols x,y]")
     add_curve("file.lis[cols x,y]")
   

   % S-Lang
     make_figure("file.lis[cols x,y]");
     add_curve("file.lis[cols x,y]");
   

   This will plot up columns x and y from the file file.lis.

2. Three columns: A set of (x,y) points with symmetric errors on y.

   # Python
     make_figure("file.lis[cols x,y,dy]")
     add_curve("file.lis[cols x,y,dy]")
   

   % S-Lang
     make_figure("file.lis[cols x,y,dy]");
     add_curve("file.lis[cols x,y,dy]");
   

   This will plot up columns x and y from the file file.lis, and draw symmetric error bars whose length is given by the dy column. The dy values should be >= 0.

3. Four columns: A set of (x,y) points with asymmetric errors on y.

   # Python
     make_figure("file.lis[cols x,y,dylo,dyhi]")
     add_curve("file.lis[cols x,y,dylo,dyhi]")
   

   % S-Lang
     make_figure("file.lis[cols x,y,dylo,dyhi]");
     add_curve("file.lis[cols x,y,dylo,dyhi]");
   

   This will plot up columns x and y from the file file.lis, and draw asymmetric error bars whose lengths are given by the dylo and dyhi columns (which should both be >= 0).